<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>{% block title %}practice {% endblock %}for onion</title>
</head>
<body>
{% include "app/nav.html" %}{# 导航栏 #}

{# content #}
{% block contener %}
    <div>this is main page</div>
{% endblock %}

{# this is footer #}
{% include "app/bottom.html" %}

{% include "app/nav.html" %}

</body>
</html>